It's a bit of a chicken and egg problem. I think one of the big problems you have is that there is no "controller" role here. Most games have specific object types and reactions. I don't see how you can get away without some cascading if you have abitrary objects and rules.

Let's say you have two objects ($foo and $bar). You want them to bounce off each other if they collide, how can you do it? If you check $foo before moving and finds it will collide with $bar, it's easy enough to change $foo's movement, but $bar won't be aware of the interaction. You could come up with a way for $foo to tell $bar they collided, but that still leaves other issues.

You also have a problem with the order of movements. Let's say $foo is at 0,0 and $bar is at 1,0. Both of them are traveling right 1 column per frame. $foo will always hit $bar even though they shouldn't.

You can't just check to see if a cell is occupied after a movement to detect collisions either as an object might move 5 cells at a time. (So $bar could go right through $foo with a large enough movement)

Perhaps the best way is to do the movements ( keeping track of the last positions in the object as well) flagging objects that have collided and returning them. (Detecting the collisions could be a little hairy)

Then the programmer can decide what to do (such as handling the interaction, moving the objects and run_callback_routines() again (taking care to avoid infinite loops of course)


-Lee

"To be civilized is to deny one's nature."

In reply to Re: Collision detection quandry by shotgunefx
in thread Collision detection quandry by robobunny

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